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The SOC1 MADS‐box gene integrates vernalization and gibberellin signals for flowering in Arabidopsis
Author(s) -
Moon Jihyun,
Suh SungSuk,
Lee Horim,
Choi KyuRi,
Hong Choo Bong,
Paek NamChon,
Kim SangGu,
Lee Ilha
Publication year - 2003
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2003.01833.x
Subject(s) - vernalization , gibberellin , mads box , flowering locus c , arabidopsis , transcription factor , mutant , biology , psychological repression , gene , regulator , microbiology and biotechnology , genetics , gene expression
Summary The floral transition in Arabidopsis is regulated by at least four flowering pathways: the long‐day, autonomous, vernalization, and gibberellin (GA)‐dependent pathways. Previously, we reported that the MADS‐box transcription factor S UPPRESSOR OF O VEREXPRESSION OF C O 1 (SOC1) integrates the long‐day and vernalization/autonomous pathways. Here, we present evidences that SOC1 also integrates signaling from the GA‐dependent pathway, a major flowering pathway under non‐inductive short days. Under short days, the flowering time of GA‐biosynthetic and ‐signaling mutants was well correlated with the level of SOC1 expression; overexpression of SOC1 rescued the non‐flowering phenotype of ga1‐3 , and the soc1 null mutant showed reduced sensitivity to GA for flowering. In addition, we show that vernalization‐induced repression of FLOWERING LOCUS C ( FLC ), an upstream negative regulator of SOC1 , is not sufficient to activate SOC1 ; positive factors are also required. Under short days, the GA pathway provides a positive factor for SOC1 activation. In contrast to SOC1 , the GA pathway does not regulate expression of other flowering integrators FLC and FT . Our results explain why the GA pathway has a strong effect on flowering under short days and how vernalization and GA interact at the molecular level.